The present invention relates to a pneumatic controller.
Pressure transducers typically include at least first and second pressure ports. The first pressure inlet port is normally attached to a high pressure inlet line and the second pressure port is normally attached to a lower pressure outlet line. The pressure transducer receives an input signal indicative of the desired output pressure. The pressure transducer is intended to provide the desired output pressure with little flow between the input and output pressure lines. The transducer may include a single diaphragm or other sensor element affected by the input pressure and input signal to provide the desired output pressure, or it may include two separate pressure transducers.
Such pressure transducers are most commonly provided as a stand-alone device. Installation in the field may require two or more individuals, namely, an electrician to run the electrical lines and a plumber or pipe-fitter to run the fluid lines. Additionally, the plumber or pipe-fitter may install an isolation valve on the high pressure input line. The isolation valve can be closed to close off or “isolate” the high pressure line from the pressure elements.
Pressure transducers assemblies may incorporate both the transducer(s) and the isolation valve assembly as a single product, and thus require less field installation time. In particular, the connections made between the isolation valve and the pressure transducer(s) may be made as a manufacturing step for the assembly rather than in the field.
In many cases, input control signals are provided from a remote controller using a voltage signal, current signal, or digital input signal. In this manner, the output pressure may be remotely controlled. In order to control the pressure transducer and thus the output pressure, the controller is programmed with suitable instructions to provide the desired input signals at the desired times.